UC5613

The UC5613 provides 9 lines of active termination for a SCSI (Small Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the cable segment.

The UC5613 provides a disconnect feature which, when opened or drivenhigh, disconnects all terminating resistors and disables the regulator greatly reducing standby power. The output channels remain high impedance even without Termpwr applied. A low channel capacitance of 3pF allows units at interim points of the bus to have little or no effect on the signal integrity.

The UC5613 is pin-for-pin compatible with its predecessor, the UC5603 - 9 line Active Terminator. The only functional difference between the UC5613 and UC5603 is the absence of the negative clamps. Parametrically, the UC5613 has a 5% tolerance on impedance and current compared to a 3% tolerance on the UC5603. Custom power packages are utilized to allow normal operation at full power (1.2 watts).

Internal circuit trimming of UC5613 is utilized, first to trim the impedance to a 5% tolerance; then, the output current is trimmed to a 5% tolerance. The output current trim is set as close as possible to the maximum value of the SCSI specification which maximizes the noise margin for fast SCSI operation. Other features include thermal shutdown and current limit.

This UC5613 is offered in low thermal resistance versions of the industry standard 16 pin narrow body SOIC, 16 pin ZIP (zig-zag in line package), and 24 pin TSSOP.